you kidding me? your nick is my real name with an extra l and a k instead of a c, and one of your first posts is about animation? bizarre. I think the first art I posted here was a jump animation :p. Only strange thing is you're at germany, is Camilo a common name over there too? doubt it...tal vez eres hispano pero te mudaste?
anyways.
most pixelart animator guys use Graphics Gale for animation (me included) there's also Cosmigo Promotion which is a bit more cumbersome to get into but it has it's own advantages, it can turn any animation into a brush which should be usfeul for effects and making backgrounds.
animation looks ok, it's functional in a limited sort of way. I dont think there's anything wrong but clearly you want to make it cooler. Do you have any major influences? is your idea of cool movment SuperBros of Sword&Sworcery? or Ohira of Kid's Syory? (just taking wild guesses from the thick character with the thin limbs)
one thing that strikes me right away is that there's no fully redrawn frames, this is not wrong but it's a limitation when you compare it to hand drawn animation where that would never happen. You dont have to redraw EVERY frame but try to redraw the key poses that are important for the animation, that way your pixels dont look inferior to hand drawn animation.
for example when he's running he's still half facing the camera, it's customary in games but it makes the run look half assed. He's got sot of a ninja run with the arms by the side but the arms just wobble behind him and he's still facing the camera, I cant tell if you want a half-hearted run (Cause he's a lazy rabbit or whatever) or if you want a ninja run.
if it's a ninja run he should be looking straight to the side and with his torso more lowered, when ninjas run they seem like they're being suspended by their torsos and their legs go really fast to the point of motion blur below them
this is an extremely simple ninja run but it makes the point.
I agree that the ilde is boring. Breathing ildes just say nothing about the character and I have a hard time picturing that at all outside of games. Again it's not wrong it' super common but if you want to make him cooler you can defenitively do something else there. if you dont want to you could just have more frames in the same anim to make it smoother, it could work
you can have him do a loop of animation but try to have some intent behind it, try to think why the guy would do that eeevery time he stopped
http://www.fightersgeneration.com/characters3/ramon-a.html this is a character that pulls it off, he has a sort of dancey ilde but when he walks it looks like a modification of that dance, so it makes sense that he's doing that to be able to quickly move if he wants to attack or avoid.
if you're not gonna have him do a looped ilde, maybe you could have him do a transition from fight-stance to regular stance, that gives him some more character, it's fitting for a character that tries to have some composure.
These anims communicate more character than regular breathing, that's something I try to think about when I make an animation, I try to think of wether this is a guy that fights calmly or angrily, wether he's precise or sloppy, etc.
You have a human-bunny here, if I had a character like that I'd try to find an interesting inbetwen point between human motion and bunny motion, watch videos of bunnies moving around and imagine what a hybrid of that and humans would be like, then animate that.
So, dunno that's some rambling of what I would maybe do with this if I was tasked with changing the animations, but it's all your decision which is why I'd like to know what you think is really cool movment, what it is you're trying to reach towards with this, so please do tell.